refactor: enhance env variable usage

Cargo.lock

@@ -1046,6 +1046,7 @@ dependencies = [
  "reqwest",
  "secrecy",
  "serde",
+ "serde-aux",
  "serde_json",
  "sqlx",
  "tokio",
@@ -1849,6 +1850,17 @@ dependencies = [
  "serde_derive",
 ]
 
+[[package]]
+name = "serde-aux"
+version = "4.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a86348501c129f3ad50c2f4635a01971f76974cd8a3f335988a0f1581c082765"
+dependencies = [
+ "chrono",
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "serde_derive"
 version = "1.0.193"

Cargo.toml

@@ -18,6 +18,7 @@ hyper = { version = "1.1.0", features = ["full"] }
 # Serde / json
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1"
+serde-aux = "4"
 # serde_with = "3"
 # Axum
 axum = { version = "0.7" }

src/configuration.rs

@@ -1,4 +1,5 @@
 use secrecy::{ExposeSecret, Secret};
+use serde_aux::field_attributes::deserialize_number_from_string;
 
 #[derive(serde::Deserialize)]
 /// The setting collection.
@@ -16,6 +17,7 @@ pub struct Settings {
 /// * `port`: The port to listen on
 /// * `host`: The host address to listen on
 pub struct ApplicationSettings {
+    #[serde(deserialize_with = "deserialize_number_from_string")]
     pub port: u16,
     pub host: String,
 }
@@ -31,6 +33,7 @@ pub struct ApplicationSettings {
 pub struct DatabaseSettings {
     pub username: String,
     pub password: Secret<String>,
+    #[serde(deserialize_with = "deserialize_number_from_string")]
     pub port: u16,
     pub host: String,
     pub name: String,
@@ -88,6 +91,11 @@ pub fn get_configuration() -> Result<Settings, config::ConfigError> {
         .add_source(config::File::from(
             configuration_directory.join(environment_filename),
         ))
+        .add_source(
+            config::Environment::with_prefix("APP")
+                .prefix_separator("_")
+                .separator("__"),
+        )
         .build()?;
 
     settings.try_deserialize::<Settings>()